Device for covering electric wires



June 6, 1944. F. KLUTEfEI AL DEVICE-FOR COVERING ELECTRIC WIRES FiledD86. 10. 1938 2m 2 PM Patent ed June 6, 1944 UNITED STATES. PATE NTOFFICE v DEVICE FOR COVERING ELECTRIC WIRES Friedrich Klute and HarryHeering, Berlin- Charlottenburg, Germany; vested in the Allen PropertyCustodian Application December 10, 1938, Serial No. 245,052 In GermanyDecember 10, 1937 3 Claims.

in one plane through correspondingly grooved rolls together with bandsconsisting of insulating material and supplied from above and below. Thelongitudinal covering is particularly employed in the manufacture ofrubber insulated conductors.

The application of the longitudinal covering in connection with theemployment of artificial materials available for some time past on themarket presents considerable difficulties. En-. deavors had already beenmade to overcome these difiiculties by adding a higher percentage ofsoftening agents, which, however, was not successful. Also the heatingof the hands before passing through the grooved rolls could not removethe difficulties owing to the greater tenacity of the artificialsubstances as compared with rubber. Consequently, it has recently beenproposed to dispense with longitudinal covering in the case so as toattain a proper meshing of the different rolls with one another.

This invention may be employed for thermoplastic insulating materials ofany description which are suitable for the manufacture of electrio wirecoverings, i. e., also for the natural insulating materials hithertoemployed in the manufacture of longitudinal coverings. However, theparticular advantage of the invention consists in the possibility ofemploying tenacious artificial substances for the manufacture of lonofartificial substances and to employ the squirt- I ing method, for whichpurpose a'plurality of squirting dies lying in one plane were employedin order to render the squirting method more economical.

According to this invention the manufacture of bands of insulatingmaterial by means of calenders is combined with the manufacture ofsheathings for the conductors by means of .g'rooved rolls into oneoperation by supplying the bands produced on the calenders directly tothe grooved rolls together with the conductors to be multistage rollingmill whose initial stages con-' sist of heated calender rolls and whoseend-stage consists of grooved rolls also heated. It may be preferable toemploy a fouror multistage rolling mill in order to heat up theartificial" material in a particularly uniform manner, in which case therolls for the initial stages may also be provided with more or less deepgrooves gitudinal coverings. Such artificial substances are, forinstance, thepolyvinyl halides with or without re-halogenation, thevinyl mixed polymats and finally also the synthetic rubber hydrocarbons;These artificial materials may be treated according to the inventioneven without softening agents or without adding small'quantitles ofsofteners thereto, which is of particular importance, since the electricproperties of the, softening agents are inferior to those of the'artific al materials. Consequently, coverings made by the squirtingmethod and consisting of mix: tures containing 25 to softening agents.are less favorable from an electrical point of view than thelongitudinal-coverings manufactured according to the invention.Furthermore, these longitudinal coverings are more economical ow ing tothe saving in softeners. I

An arrangement for carrying the invention into practice is shown by wayof example in the accompanying drawing. This arrangement consists of arolling mill having, for instance, four stages, in which two bands ofartificial material are manufactured and supplied from above and belowto the conductor l to be covered. The rolling mill is designed in assymmetrical a manner as possible and presents the same number of rollsfor both bands which are produced aboveand below the conductors Iinserted in the central.

stage consisting of the'rolls 6 and I to be applied 1 to the conductorsI. The rolls 2, 3 and Bare plain. whereas the'roll 1 is grooved as isthe case with the longitudinal covering machines hitherto employed. Therolls 2', 3, 6' and l which produce the band 5' from the material 4' arecorrespondingly arranged below the conductors I. Under the pressure ofthe rolls. .1 and l' which direction of the rolls. As a form the fourthstage the bands 5 and 5 are integrally combined to form the covering 8surrounding the conductor l. v

i The width of the rolling mill depends upon the number of theconductors l to be simu1taneously covered and arranged side by side inaxial rule, the rolling mill is therefore not as wide as the usualcalendars. If it is not possible to produce sufliciently homogeneousbands from the material 4, 4 owing to the smaller width of the roll itis advisable either to arrange one more pair of rolls than is otherwisenecessary or to give the bands such a width that they project beyond therow of conductors a greater amount than is the case with'the methodshitherto known for manufacturing longitudinal coverings.

Some artificial substances particularly those containing polyvinylchloride have the peculiarity that their good properties as to theirstrength and for instance, by electrically heating the rolls, for

which purpose well known control devices not shown here may be employed,particularly automatic control devices. When heating the rolling mill bysteam such control devices may also be employed. Particularlyadvantageous is the housing of the entire rolling mill so that astrictly uniform temperature prevails therein. A housing 9 is shownschematically in the drawing. The housing is provided at its upper andlower part with hoppers for the material A and d and the rolls rolls. Itis even possible to arranged the calender rolls obliquely in front orthe grooved rolls and under given circumstances at such a distance fromthe grooved rolls that the bands do not run between the rolls for acertain distance.

The bands manufactured on' the rolls may be produced of difi'erent or atleast variegated materials if this is convenient for the manufacture anduse of the wires.

What is claimed is:

1. Device for longitudinally covering electric conductors withartificial plastic and insulating material of great tenacity,comprising'two calenders each comprising a plurality-of calender rolls,means for supplying the material in the raw state to said calendersrespectively, two grooved rolls disposed directly adjoining each otherwith their may be inspected by sight glasses or wall apertures (notshown) capable of being easily closed. The enclosure 9 may, forinstance, consist of a sheet iron housing. However, it may also be pro-.vided with walls consisting of material particularly impermeable toheat. Furthermore, heating mvices may be arranged in the walls or ontheir inner side and they may under given circumstances be so designedthat th rolls need not be heated. The bearings of the rolls may, ifnecessary, be cooled in order to enable an operation of the rolling millat a high temperature and pressure of the rolls.

The arrangement of the rolls may be different from that shown in thedrawing. The rolls may also be arranged perpendicularly one above theother. In this case the supply of the artificial substance may beeffected by the use of guides on the rolls and also by the use ofshaking troughs.

It is not necessary that the calender rolls be arranged perpendicularlyabove or below the grooved grooves in registry so as to form a passagefor the conductor to be covered, each of said grooved rolls beingarranged in contact with a roll of a different calender toreceiv thecalendered material therefrom, and means for feeding the bare conductortogether with said oalendered material through said passage between saidgrooved rolls to apply said 'material from opposite sides to saidconductor.

2. Device for longitudinally covering electric conductors withartificial plastic and insulating material of great tenacity, comprisingtwo calenders each comprising a multistage set of heated calender rolls,means for supplying the material in the raw state to said calendersrespectively, two heated grooved rolls disposed directly adjoining eachother with their grooves in registry so as to form a passage for theconductor to be covered, each of said grooved rolls being arranged incontact with a roll of a different calendar so as to form a continuationof said calender in order to receive the calendered material therefrom,and means for feeding the bare conductor together with said calenderedmaterial through said passage between said grooved rolls to apply saidmaterial from opposite sides to said conductor.

3. Device for longitudinally covering electric conductors withartificial plastic and insulating material of great tenacity, comprisingtwo calenders each comprising a multistage set of heated groovedcalender rolls, means for supplying the material in the raw state tosaid calendars re spectively, two additional grooved rolls disposeddirectly adjoining each other so as to have their grooves form a passagebetween said latter rolls,

each of said latter rolls being arranged in contact with a grooved rollof a different calender to receive the calendered material therefrom,and means for feeding the bare conductor together with said calenderedmaterial through said passage to apply said material from opposite sidesto said conductor.

FRIEDRICH KLU'IE.

HARRY HEERING.

